[Studies on IgG subclass antibodies in adult asthma. 2. Changes in serum antigen specific IgG subclass antibodies for aging and intractability in asthmatics].

To clarify the factors which induce intractable asthma, the level of serum IgG subclass antibodies to mite (Dermatophagoides farinae) and Candida antigens (Candida albicans) for aging and severity was investigated in 230 bronchial asthmatics (Male: 117, Female: 113) aged 6-81 years old (mean age = 40). Total IgE level and IgE antibodies to mite and Candida antigens were measured by radioimmunosorbent test (RIST) and radioallergosorbent test (RAST), respectively. The serum level of IgG and IgG1 antibodies to the antigens were measured by enzyme-linked immunosorbent assay (ELISA). The results were as follows: 1) The incidence of severe asthma in aged and late onset asthmatics, especially late onset intractable asthma (LOIA), was higher than that in young and early onset asthmatics. 2) The serum level of total IgE and IgE antibodies to mite in aged and late onset asthmatics was lower than that in young and early onset asthmatics. 3) The incidence of severe and intractable asthmatics in the group of low IgE levels (less than 300 IU/ml) was higher than that in the group of high IgE levels (over 500 IU/ml). The incidence of positive IgE (RAST) score to mite in severe and intractable asthmatics was lower than that in mild and moderate asthmatics. 4) Considering aging, the serum levels of IgG and IgG1 antibodies to mite and Candida in severe and intractable asthmatics was higher than those in mild asthmatics. These data indicate that the aged and late onset asthmatics may produce dominantly the IgG (IgG1) antibody to the antigens, and have severe asthma attacks caused by IgG (IgG1) rather than IgE antibody.